1. Field of the Invention
This invention relates to electronic circuits, and in particular, to circuits for interconnecting and translating logic signals from bipolar emitter-coupled logic voltage levels to complementary metal oxide semiconductor voltage levels.
2. Description of the Prior Art
With the advent of advanced process technologies, integrated circuits now may be fabricated which employ both bipolar and field effect transistors. For such circuits to function satisfactorily, interface circuitry is required to translate between the voltage levels of the various devices employed on the integrated circuit. An important criterion for such interface circuitry is the voltage at which the interface circuits change state, known as the trip point voltage. In prior art circuits, the trip point voltage was specified by a trip point reference voltage provided to each translation circuit. Unfortunately, because of variations in process parameters and manufacturing tolerances, the individual transistors in each translator will have slightly different characteristics at different locations on the integrated circuit. Thus, the trip point defined by that translator will vary from that desired.
An additional disadvantage of prior art voltage translators for interfacing bipolar and field effect devices is the current consumed by each translator. Although each translator, by itself, draws only a small current, the large number of translators required for very large scale integrated circuits resulted in considerable current and therefore excessive power consumption.